Z-Saber Challenge is a X-Buster Challenge for Zero, Except he is using Saber.
Just like X, Every weapon that Zero gain will no longer get damage against the boss and enemy(This including his Z-Buster and his Giga Attack).
Also Zero no longer having a damage overlap when using Guard Shell.
Now basically, There are two maverick that can't be beaten with SDC, They are Blaze Heatnix and Infinity Mijinion.
Blaze Heatnix weakness is his saber and buster. The only way to beat him faster is use sentsuizan(Ground Scaravich weapon/technique) which is deals 6 damage or his third slash which deals 5 damage.
In this challenge, You can no longer damage him with sentsuizan and no matter which slash you use, it always deal 3 damage.
You may wondering that this can be much harder because Zero will take high chunk of health when getting damage, So i decide to disable the lower base defense for Zero.
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https://www.youtube.com/watch?v=OKPV-Et2UQM